data_global _chemical_name_mineral 'Fluoro-eckermannite' loop_ _publ_author_name 'Oberti R' 'Hawthorne F C' 'Camara F' 'Raudsepp M' _journal_name_full 'American Mineralogist' _journal_volume 84 _journal_year 1999 _journal_page_first 102 _journal_page_last 111 _publ_section_title ; Unusual M3+ cations in synthetic amphiboles with nominal fluoro-eckermannite composition: Deviations from stoichiometry and structural effects of the cummingtonite component Sample: Ga, Na.94Na1.07Mg.93Mg4.87Ga.13Si8O22F2 ; _database_code_amcsd 0002061 _chemical_formula_sum 'Si8 Mg5.8 Ga.14 Na2.02 O22 F2' _cell_length_a 9.666 _cell_length_b 17.902 _cell_length_c 5.272 _cell_angle_alpha 90 _cell_angle_beta 102.84 _cell_angle_gamma 90 _cell_volume 889.459 _exptl_crystal_density_diffrn 3.031 _symmetry_space_group_name_H-M 'C 1 2/m 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,z' '1/2+x,1/2-y,z' '-x,y,-z' '1/2-x,1/2+y,-z' '-x,-y,-z' '1/2-x,1/2-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Si(1) 0.28440 0.08490 0.28360 1.00000 0.00557 Si(2) 0.29210 0.17070 0.78780 1.00000 0.00709 Mg(1) 0.00000 0.08890 0.50000 1.00000 0.00912 Ga(2) 0.00000 0.17980 0.00000 0.07000 0.00975 Mg(2) 0.00000 0.17980 0.00000 0.93000 0.00975 Mg(3) 0.00000 0.00000 0.00000 1.00000 0.00798 Mg(4) 0.00000 0.26430 0.50000 0.47000 0.02330 Na(4) 0.00000 0.26430 0.50000 0.53000 0.02330 NaA 0.00000 0.50000 0.00000 0.26000 0.03331 NaA(m) 0.04440 0.50000 0.10150 0.35000 0.03521 O1 0.11390 0.08500 0.21340 1.00000 0.00595 O2 0.12040 0.16950 0.72310 1.00000 0.01001 F3 0.10370 0.00000 0.70710 1.00000 0.00925 O4 0.36830 0.24850 0.78460 1.00000 0.01748 O5 0.35040 0.12840 0.06960 1.00000 0.01976 O6 0.34680 0.11870 0.57080 1.00000 0.02647 O7 0.34560 0.00000 0.28380 1.00000 0.01456